Absolutely awesome. I discovered it in late March for the first time and a lot of people I have talked to hadn't heard of it, so figured I'd pass it on. If you subscribe to HBO, you can activate an account to HBO Go and watch every episode of any show they have ever shown for free (well, besides the cost of subscribing to HBO).
It's on XBOX Live now too. Anyway, figured I'd pass the info on in case anybody hadn't heard of it yet.